Guide: Installing a solar panel on the HCH-II (step-by-step)

Discussion in 'Articles' started by msantos, May 7, 2008.

  1. msantos

    msantos Eco Accelerometrist

    Jeff, I would suspect it would cut its effectiveness significantly. Let me illustrate:
    The OEM glass tint is enough to "eat" 30-40 mA out of a 2.4W panel (120mA) and depending on angle of the solar panel vs the window glass and the light source (sun) the loss may be even higher. :(

    Obviously, tinting the rear window would not be a priority for me with a rear mounted solar panel in the wings. The front mounted SRS also make it less safe to mount the panels on the front dash. We could go with flexible or film-based panels but their power yields seem a bit low for my liking.
  2. psyshack

    psyshack He who posts articles

    That looks like a 120mm fan. Some fans you can wire up to run at 5 to 7v. A lot of 120's respond well to this and move a lot of air. Computer mod folks have been doing it for years. I do it with a reobus on my four 120mm fans for my radiator on my main water cooled rig.

    I would think it would be best to use such a fan in the IPU fan duct. I have not seen the duct yet. so maybe a 80mm fan would work.
  3. msantos

    msantos Eco Accelerometrist

    I thought about that but I decided against it because:
    1. It would be right there in the IPU air stream as a potential air-flow obstacle.
    2. I don't want warm cabin air to circulate over the critical IPU modules while the car is baking under the sun.
    3. The volume of air I can move is limited by the solar power I can produce and I prefer (for now) a larger diameter, quieter, lower RPM fan to do the job. The IPU duct cross section is too small for me and I would have to increase the air speeds to move a measurable amount of air. 55CFM max that this 120mm fan can provide may just do the trick for me.
    4. I don't want to interfere with or modify any the OEM hybrid systems. I did that in 2006 and as a result I had to replace over 50% of the IPU subsystems in order to regain my warranty. :(
    What do you think?
  4. psyshack

    psyshack He who posts articles

    Maybe the cabin ducting system then?
  5. greenrider

    greenrider Well-Known Member

    If you pull out the rear passenger side trunk liner, there's a round opening with attachment holes around it between the duct work from the IMA batteyr and the fender. It is a perfect place to mount a fan like. I'm optimistic that it would help to keep the IMA battery cool and prevent recals but would it help in cooling the cabin any?
  6. msantos

    msantos Eco Accelerometrist

    Hi Jeff and Mike;

    Toyota did integrate the solar powered blower right into the HVAC system on their 2010 Prius but I fear it would a bit of a challenge to do it on the HCH-II with the types of low power fans I was considering::
    1. There's almost not space that I can see where we may insert a fan, no matter how small, inline with the HVAC ducting.
    2. If we did, then the fan would be bombarded by very hot air in the winter. DC fans have internal circuitry and don't like a lot of heat.
    3. It would probably interfere (resistive) with the HVAC air stream when the solar powered fan it is not working.
    Now, I've been thinking about this and so far the easiest approach I see, is to place a 120mm round hole in the rear dash tray and mount the DC solar powered fan there. What this would do is draw the stale and hot air from the cabin into the trunk while the car is parked under the sun.

    Of course, the fan would be mounted under the tray (lots of room there) and we would need to put a nice grill to cover it, and that could work very well. In my case, I would not need to cover it because the solar panel would be right there, 1" right above it. This mod wold eat no trunk space at all.

    As you know, the trunk has two vent vanes on each rear corner of the vehicle so the hot air in the trunk would be forced to exit through there. At a max of 55CFM and leaving the front dash vents on open, we could see better cabin temps when arriving to a locked car in a warmer summer day.

    Hummm... maybe we could even shut off the climate control altogether when driving in a sunny day... ;)

    Now, I just put together a simple schematic for a small thermally controlled circuit to drive a 120mm DC fan and what this would do is throttle the fan according to the temperature since we don't want the darn fan to go ON during a colder winter day. In total, the little circuit will cost $2-$5 worth of components and should still allow some solar power to still make it to the battery.

    In have a feeling this mod is about to take form one of these weekends. ;)


  7. psyshack

    psyshack He who posts articles

    I have fans.... Need a panel. :)
  8. Kacey Green

    Kacey Green Well-Known Member

    I'll buy a Santos HVAC, Battery topping kit.
  9. psyshack

    psyshack He who posts articles

  10. greenrider

    greenrider Well-Known Member

    I just picked up 2 solar panels on sale at Costco today. They have an auxiliary outlet plug and 2 clamps for battery terminals. Here is my question, can I simply bypass the relay that shuts off the 12v aux power so that it is constantly hot and connect the solar panel via the aux outlet to charge the 12V battery or must I run wires as in the DIY?

    I intend to tint the side and rear windows this summer and will attach the solar panel with the included suction cups to the base of the windshield, removing it when driving. The car sits out mostly now since my wife keeps the Insight in the garage and there will be ample opportunity for solar charging.
  11. msantos

    msantos Eco Accelerometrist

    Hi Mike;

    The bypass of the relays has been performed in the past so I am pretty sure it could work for you as well.

    However, I would still suggest you run the wiring straight to a live connection on the fuse panel since that also gives you an opportunity to fuse the panel with a lower fuse value. This approach will look cleaner and compliant just in case a Honda technician ever raises the issue for whatever reason. Unfairly or not, the inferred warranty consequences can be quite severe.


  12. greenrider

    greenrider Well-Known Member

    Good point. Since I already have the fog lights in the #6 slot, I assume any slot will work?
  13. msantos

    msantos Eco Accelerometrist

    Use a volt meter on the remaining empty ones to confirm but you should be OK with an alternate socket.
  14. ejbhch

    ejbhch Member

    Hi Manuel,

    My only add-on accessory on my HCHII is an electronic anti-rust system installed by Honda when I bought the car. Since my car is usely sitting in my drive way (I don't commute anymore, being retired) I was tinking of using a small battery charger installed under the hood that I could connect from time to time to charge the 12 volt battery. This way I could charge it to its maximum every time if I can. What do you think?


    Jean Binette, Dunham, Qu├ębec
  15. msantos

    msantos Eco Accelerometrist

    Hi Jean;

    Those electronic anti-rust systems can be real power hogs on the poor 12V battery... I should know since depending on the weather conditions, mine actually consumes varying amounts of power.

    So yes, that is a great idea. I wholeheartedly agree on getting a battery tender or some other SLA generic charger plugged onto it. ;)

    BTW: Welcome to CleanMPG !!!! :D

  16. 06hch2

    06hch2 Well-Known Member

    Hi Manuel,
    I'm looking around the web for a solar panel for my car, and there are a lot of different options and terms out there (eg, amorphous, mono/polychrystallline, overcharge/discharge protection). What features and electrical parameters should I be looking for in a solar battery maintainer for my car? Anything I should avoid?
  17. msantos

    msantos Eco Accelerometrist

    Hi Matt;

    Amorphous panels are the most affordable and still quite effective for low power operations. The ones that I have used have served me very well and I got lots to show for it. Not only the 12V battery on my 2006 HCH is as good as new after 3+ years (NO JOKE) but the same can be said of other cars that had the same retrofit shortly after (HCH-II's and Prius-IIs).

    And we all know what happens when the 12V charge is less than optimal? Yes, shorter lived battery and less than optimal FE for the time it lasts - and that is the truth.

    However, the thing to watch for when using a solar panel, is overcharging the 12V battery. Even though a small 2-5 Watt panel may not seem like much, the darn things will work very well when left in the sun for extended periods of time. Any power above 5W will probably require a charge controller to avoid overcharging the 12v battery. Fortunately, these charge controllers are not very expensive ($20-$30) and work very well.

    Discharge protection refers to the presence of a (2 cent) diode that prevents the current from flowing in the reverse direction... which at night would drain power from the battery. Almost all consumer ready small panels have this built-in.

    With all this said, I have upgraded my solar arrangement yet again. This time to mono-crystalline VERY lightweight panels producing 10-50 watts. This is because my demands have also gone up substantially and I am also eying even more benefits.

    I'll post some pictures soon. ;)


  18. cephraim

    cephraim Noob

    I ended up pulling my solar panel out of my Altima Hybrid, as I could not measure any FE benefit to it in my car.
  19. 06hch2

    06hch2 Well-Known Member

    Thanks, Manuel. Can't wait to see your latest upgrade.
  20. 06hch2

    06hch2 Well-Known Member

    Turns out you got an outstanding deal with the 2.4 watters for $10. After an exhaustive web search, unable to find a deal anywhere near as good as yours, I decided to go with a couple of the 1.5 watt Coleman units offered by Costco. Do you see any problems attaching the positive wire directly to the fuse box with a fuse like you did with the tpms unit?

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